The geostationary orbit satellites are used for communication, broadcasting, meteorological observation, etc. and have become important social infrastructures. If large debris collision has occurred in the geostationary orbit, we become unable to use this orbit. However, it is very difficult to track or even to detect small objects from the ground-based sensors. In this paper we describe space debris detection with an optical sensor on-board stellite, debris avoidance system and future plan.会議情報: 第59回宇宙科学技術連合講演会（2015年10月7日-9日. かごしま県民交流センター), 鹿児島市, 鹿児島県形態: カラー図版ありタイトルの誤記: Space Based Optical Observation of Space BebrisPhysical characteristics: Original contains color illustrations